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Question 1
Incorrect
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A 61-year-old woman, present to her general practitioner. She complains of a severe lancinating pain in her forehead that only last a few seconds, possibly triggered by washing her face, occurring over the previous six weeks.
On examination, she is normal with no other signs or symptoms.
Which nerve is the most likely cause of her pain?Your Answer: Somatic sensory fibres of the vagus nerve
Correct Answer: Sensory branches of the ophthalmic division of the trigeminal nerve
Explanation:Her symptoms are suggestive of trigeminal neuralgia which is a short, sudden, severe sharp unilateral pain in the facial region. The pain often follows the sensory distribution of the trigeminal nerve (CN V).
The trigeminal nerve gives rise to 3 sensory and 1 motor nuclei. Neuralgia can arise from any of the 3 sensory divisions.
The ophthalmic division gives rise to 3 further sensory branches, which are the frontal, lacrimal and nasociliary.
The frontal branch of the ophthalmic division of the trigeminal nerve is responsible for the innervation of the area in question.
The superior alveolar dental, zygomatic and sphenopalatine nerves are all branches arising from the maxillary division of the trigeminal nerve.
The mandibular division of the trigeminal nerve provides sensory and motor innervation. The sensory innervation is carried out by the auriculotemporal nerve which supplies the lower third of the face, while the motor fibres are responsible for controlling the muscles of mastication.
The somatic sensory branches of the vagus nerve are responsible for sensory innervation of the external acoustic meatus and tympanic membrane.
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This question is part of the following fields:
- Pathophysiology
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Question 2
Incorrect
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The mandibular division of the trigeminal nerve passes through which anatomic structure?
Your Answer:
Correct Answer: Foramen ovale
Explanation:The mandibular branch of the trigeminal nerve passes through the foramen ovale. Other structures that pass through this foramen are the accessory meningeal artery, and occasionally, the lesser petrosal nerve.
These are the structures that pass through the other openings in the cranial fossa:
Foramen rotundum – Maxillary branch of the trigeminal nerve
Foramen lacerum – Greater petrosal nerve, traversed by the internal carotid artery
Superior orbital fissure – Oculomotor nerve; trochlear nerve; lacrimal, frontal and nasociliary branches of the ophthalmic branch of the trigeminal nerve; abducens nerve, superior ophthalmic vein
Stylomastoid foramen – facial nerve
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This question is part of the following fields:
- Anatomy
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Question 3
Incorrect
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Which statement most accurately describes the action of increasing the gain in ultrasound imaging?
Your Answer:
Correct Answer: Amplifies the returning signal
Explanation:A higher frequency ultrasound comes with a better resolution of the digital image. Ultrasound with a frequency of 15 MHz is best used in imaging of superficial organs such as the thyroid gland, muscles, tendons and breasts whereas deep organs are better imaged using a lower frequency of 2-7MHz because of its ability for deeper penetration but lower resolution. These low frequency probes are also used to diagnose ascites, pleural effusions or can be used in echocardiography.
The US probe emits and then absorbs a reflected wave. Similar to brightness control, increasing the gain will amplify the return signal which is then attenuated by the tissue. This increases the signal to noise ratio.
A high frame rate, which basically means the number of times an image is updated onto the screen per second, improves the resolution of a moving 3D image which has become more accurate as the computing power has increased.Widening of the image field can be obtained by altering the penetration depth which is obtained by changing the frequency of the US beam
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 4
Incorrect
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Which of the following best explains the association between smoking and lower oxygen delivery to tissues?
Your Answer:
Correct Answer: Left shift of the oxygen dissociation curve
Explanation:Smoking is a major risk factor associated with perioperative respiratory and cardiovascular complications. Evidence also suggests that cigarette smoking causes imbalance in the prostaglandins and promotes vasoconstriction and excessive platelet aggregation. Two of the constituents of cigarette smoke, nicotine and carbon monoxide, have adverse cardiovascular effects. Carbon monoxide increases the incidence of arrhythmias and has a negative ionotropic effect both in animals and humans.
Smoking causes an increase in carboxyhaemoglobin levels, resulting in a leftward shift in which appears to represent a risk factor for some of these cardiovascular complications.
There are two mechanisms responsible for the leftward shift of oxyhaemoglobin dissociation curve when carbon monoxide is present in the blood. Carbon monoxide has a direct effect on oxyhaemoglobin, causing a leftward shift of the oxygen dissociation curve, and carbon monoxide also reduces the formation of 2,3-DPG by inhibiting glycolysis in the erythrocyte. Nicotine, on the other hand, has a stimulatory effect on the autonomic nervous system. The effects of nicotine on the cardiovascular system last less than 30 min.
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This question is part of the following fields:
- Physiology
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Question 5
Incorrect
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A 35-year-old male presents to GP presenting an area of erythema which was around a recent cut on his right forearm. He was prescribed a short course of antibiotics and after 5 days again presented with progressive fatigue, headaches, and fevers.
On clinical examination:
Oxygen saturation: 98% on room air
Respiratory rate: 22 per minute
Heart rate: 100 beats per minute
Blood pressure: 105/76 mmHg
Temperature: 38.2 degree Celsius
On physical examination, a dramatic increase in the area of erythema was noted.
Blood culture was done in the patient and indicated the presence of bacterium containing beta-lactamase. Which of the following antibiotics was likely prescribed to the patient?Your Answer:
Correct Answer: Amoxicillin
Explanation:Ciprofloxacin belongs to the quinolone group of antibiotics, and doxycycline and minocycline are tetracyclines. So, they are not affected by beta-lactamase.
However, amoxicillin is a beta-lactam antibiotic and beta-lactamase cleaves the beta-lactam ring present in amoxicillin. This results in the breakdown of the antibiotic and thus the area of erythema dramatically increased.
Co-amoxiclav contains amoxicillin and clavulanic acid which protects amoxicillin from beta-lactamase. -
This question is part of the following fields:
- Pharmacology
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Question 6
Incorrect
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The average diastolic blood pressure of a control group was found out to be 80 with a standard deviation of 5 in a study aimed at exploring the efficiency of a novel anti-hypertensive drug. The trial was randomised.
Making an assumption that the data is normally distributed, find out the number of patients that had diastolic blood pressure over 90.Your Answer:
Correct Answer: 3%
Explanation:Since the data is normally distributed, 95% of the values lie with in the interval 70 to 90. This can be calculated as follows:
Interval= Mean ± ( 2 times standard deviation)
= 80 ± 2(5)
= 80 ± 10
= 70 & 90The rest of the 5% are distributed symmetrically beyond 90 and below 70 which means 2.5% of the values lie above 90.
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This question is part of the following fields:
- Statistical Methods
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Question 7
Incorrect
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You are given an intravenous induction agent. The following are its characteristics:
A racemic mixture of cyclohexanone rings with one chiral centre
Local anaesthetic properties.
Which of the following statements about its primary mechanism of action is most accurate?Your Answer:
Correct Answer: Non-competitive antagonist affecting Ca2+ channels
Explanation:Ketamine is the substance in question. Its structure and pharmacodynamic effects make it a one-of-a-kind intravenous induction agent. The molecule is made up of two cyclohexanone rings (2-(O-chlorophenyl)-2-methylamino cyclohexanone and 2-(O-chlorophenyl)-2-methylamino cyclohexanone). Ketamine has local anaesthetic properties and acts primarily on the brain and spinal cord.
It affects Ca2+ channels as a non-competitive antagonist for the N-D-methyl-aspartate (NMDA) receptor. It also acts as a local anaesthetic by interfering with neuronal Na+ channels.
Ketamine causes profound dissociative anaesthesia (profound amnesia and analgesia) as well as sedation.
Phenoxybenzamine, an alpha-1 adrenoreceptor antagonist, is an example of an irreversible competitive antagonist. It forms a covalent bond with the calcium influx receptor.
Benzodiazepines are GABAA receptor agonists that affect chloride influx.
Flumazenil is an inverse agonist that affects GABAA receptor chloride influx.
Ketamine is a cyclohexanone derivative that acts as a non-competitive Ca2+ channel antagonist.
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This question is part of the following fields:
- Pharmacology
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Question 8
Incorrect
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A pulmonary function tests results are:
Measurement Predicted result Test result
Forced vital capacity (FVC) (btps) 3.85 2.36
Forced expiratory volume in 1 second (FEV1) (btps) 3.34 0.97
FEV1/FVC ratio % (btps) 85.1 39.9
Peak expiratory flow (PEF) (L/second) 7.33 2.11
Maximum voluntary ventilation (MVV) (L/minute) 116 44.4
What does this indicate?Your Answer:
Correct Answer: Moderate restrictive and severe obstructive picture
Explanation:Severity of a reduction in restrictive defect (%FVC) or obstructive defect (%FEV1/FVC) predicted are classified as follows:
Mild 70-80%
Moderate 60-69%
Moderately severe 50-59%
Severe 35-49%
Very severe <35% This patient has a mixed deficit with a severe obstructive deficit as %FEV1/FVC predicted is 46.9% and a moderate restrictive deficit as %FVC of predicted is 61.3 FEV1/FVC ratio 80% < predicted and VC < 80% = mixed picture. FEV1/FVC ratio 80% < predicted and VC > 80% = obstructive picture.FEV1/FVC ratio 80% > predicted and VC > 80% = normal picture.
FEV1/FVC ratio 80% > predicted and VC < 80% predicted= restrictive picture.
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This question is part of the following fields:
- Clinical Measurement
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Question 9
Incorrect
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Concerning drug dose and response, one of the following statements is correct?
Your Answer:
Correct Answer: Intrinsic activity determines maximal response
Explanation:Dose response curves are plotted as % response to drug against Logarithm of drug concentration. The graph is usually sigmoid shaped.
Any drug that has high affinity and high intrinsic activity is likely an agonist. A drug with high affinity but no intrinsic activity will act as an antagonist. Displacement of an agonist also depends on the relative concentrations of the two drugs at the receptor sites.
Maximal response may be achieved by activation of a small proportion of receptor sites.
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This question is part of the following fields:
- Pharmacology
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Question 10
Incorrect
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Which of the following statements is an accurate fact about the vertebral column?
Your Answer:
Correct Answer: Herniation of intervertebral disc between the fifth and sixth cervical vertebrae will compress the sixth cervical nerve root
Explanation:The vertebral (spinal) column is the skeletal central axis made up of approximately 33 bones called the vertebrae.
Cervical disc herniations occur when some or all of the nucleus pulposus extends through the annulus fibrosus. The most commonly affected discs are the C5-C6 and C6-C7 discs. Each vertebrae has a corresponding nerve root which arises at a level above it. This means that a hernation of the C5-C6 disc will cause a compression of the C6 nerve root.
The foramen transversarium is a part of the transverse process of each cervical vertebrae, however, the vertebral artery only runs through the C1-C6 foramen transversarium.
The costal facets are the point of joint formation between a rib and a vertebrae. As such, they are only present on the transverse processes of T1-T10.
The lumbar vertebrae do not form a joint with the ribs, nor do they possess a foramina in their transverse process.
Intervertebral discs are thickest in the cervical and lumbar regions of the spinal column. However, there are no discs between C1 and C2.
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This question is part of the following fields:
- Pathophysiology
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